Flexofold prop corrosion

Tranona said:
All we need now is one of the key suspects to be found murdered in the last minutes of the episode and the next one not until a week's time.

How will we get through the week not knowing?
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Launching Wednesday, might fiddle then! Most of me thinks the stray voltage will still be there with all batteries unhooked...

So we KNOW it isn't the shaft and prop that has the charge, its is completely isolated by the flexible coupling with no wires anywhere near it, so, Mr Watson, we can discount that. What if there is current leaking into the negative system then? So the anode is getting the 200MV charge and is earthing to the... unearthed... shaft? ... but then there is no circuit between the shaft and the anode anyway?? Gah :beaten:
 
Tranona said:
Really pleased I have a saildrive, no 1,2 both switches and a galvanic isolator.
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I saw a relatively new Arcona last year, with a saildrive leg that looked like a honeycomb. I bet the owner was so pleased to have one ,as you seem to be
I much prefer my shaft :love-struck:
 
MagicalArmchair said:
Launching Wednesday, might fiddle then! Most of me thinks the stray voltage will still be there with all batteries unhooked...
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I know this is frustrating, but finding a leak will be easier ashore and it can't be that hard on a relatively simple setup. Sorry to be a killjoy, but a stray current is way worse than galvanic issues and could conceivably intensify and wreck your prop in no time - to the point it disintegrates.

I'd personally burn the midnight oil to either find it, or determine it is a false reading!
 
Tranona said:
All we need now is one of the key suspects to be found murdered in the last minutes of the episode and the next one not until a week's time.

How will we get through the week not knowing?
Click to expand...

This story is supposedly true. A cartoon series in a major newspaper (many years ago) concerned a private detective who always solved his cases. The author was told that his services were no longer required, but that the series would continue, authored by somebody else. He manoeuvred the detective into an impossible situation in his final episode, bound and gagged in a locked cellar, water rising and already up to his nostrils. He then walked out. The next author began - "with one bound our hero was free!"

Perhaps that will happen here? :)
 
CCJ said:
I saw a relatively new Arcona last year, with a saildrive leg that looked like a honeycomb. I bet the owner was so pleased to have one ,as you seem to be
I much prefer my shaft :love-struck:
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That maybe the case, but there are literally tens of thousands of saildrives going back 40 odd years that do not have any corrosion problems.

Shafts are not as trouble free as you think as this thread is illustrating. Plenty of threads on here from folks with shaft related problems.
 
MagicalArmchair said:
Launching Wednesday, might fiddle then! Most of me thinks the stray voltage will still be there with all batteries unhooked...
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I might be proved wrong Mark, but I have to say that if you manage to find a 250 mA current on a boat out of the water and with all batteries, shore power, solar panels and wind generator disconnected, then you are going to be a multi-billionaire in a very short time. Elon Musk is your friend. ;)

Richard
 
MagicalArmchair said:
Launching Wednesday, might fiddle then! Most of me thinks the stray voltage will still be there with all batteries unhooked...

So we KNOW it isn't the shaft and prop that has the charge, its is completely isolated by the flexible coupling with no wires anywhere near it, so, Mr Watson, we can discount that. What if there is current leaking into the negative system then? So the anode is getting the 200MV charge and is earthing to the... unearthed... shaft? ... but then there is no circuit between the shaft and the anode anyway?? Gah :beaten:
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With the boat back in the water it might be informative to measure the current (in milliamps) that flows from the pprop ito the water. You can do this with the meter on a DC mA range connected between the twohalves of the ccoupling with the bridging removed noting also the polarity of any current you measure. The magnitude and direction of flow should enable some estimate to be made of the seriousness of the situation.
 
RichardS said:
I might be proved wrong Mark, but I have to say that if you manage to find a 250 mA current on a boat out of the water and with all batteries, shore power, solar panels and wind generator disconnected, then you are going to be a multi-billionaire in a very short time. Elon Musk is your friend. ;)

Richard
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I think you will find that the OP has not infact made any measurements of current flow. All the readings are of voltage.
 
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